Circular knitting machine



July 2, 1 963 r B. F. COILE CIRCULAR KNITTING MACHINE Filed 001.- 31,1958 IN VEN TOR. (Be/jam; FFan/f/in Qi/e United States Patent "ice3,095,717 CIRCULAR KNITTING MACHINE Benjamin Franklin Coile, Athens,Ga., assignor to Textile Machine Works, Wyomissing, 'Pa., a corporationof Pennsylvania Filed Oct. 31, 1958, Ser. No. 771,035 2 Claims. (Cl.66-8) This invention relates to a cam structure for circular knittingmachines and more particularly such cam structure for controlling themovements of the needles during stitch drawing operations.

In circular knitting machines, radially movable sinkers cooperate with acircular series of independently movable needles in drawing yarn to formthe stitches of a knitted fabric. The needles are moved downwardly in awave by cam means to engage and draw the yarn through the previouslyformed stitches on the needles and over the stitch drawing surfaces ofthe sinkers which are then advanced in timed relationship to the needlesto place the nibs thereof above the newly drawn stitches to hold them asthe needles rise to latch clearing level. -As the .needles are againmoved downwardly to engage the yarn and draw the stitches for the nextcourse, the sinkers are retracted to remove the nibs from above thestitches on the needles so that the yarn may again be drawn over thestitch drawing surfaces of the sinkers.

In machines in which the stitches are drawn over the nibs of the sinkersas heretofore built, the relative movements of the needles and sinkersis very critical and must be so timed that as a needle reaches itsmaximum stitch drawing depth between a pair of sinkers, the stitch isready to drop off ofthe nib of the leading sinker of the pair before thenext needle starts to draw its stitch between the pair of sinkersassociated therewith. In such operation the needles continue downwardlyto draw the stitches through the previously formed stitches and onto theknockover surfaces of the sinkers after which the sinkers are advancedto place the nibs above the new stitches to hold them as the needlesagain rise to latch clearing level. If the timing is incorrect and asecond needle starts drawing its stitch 'before the first needlecompletes its stitch drawing movement, not only are stitches drawn toincorrect lengths but in many instances the increase in tension appliedto the stitch when coupled with the movement of the sinker through thestitch causes it to be broken or severed. Also in this method of drawingstitches, it sometimes occurs that when changing from one size yarn toanother, the necessary change in loop length cannot be obtained byvertical adjustment of the stitch cam so that the height of the sinkersmust also be changed.

It is therefore an object of the invention to provide means in acircular knitting machine for overcoming the above mentioned and otherdifliculties encountered in the formation of knitted fabric.

Another object of the invention is the provision of cam means in acircular knitting machine for controlling the stitch drawing movementsof the needles whereby the tension exerted by the needle on a stitch isrelieved prior to the stitch drawing operation of the next needle.

-A further object of the invention is the provision of 3,995,717Patented July 2, 1963 apparent from the following detailed descriptionof the illustrative embodiment of the invention shown in theaccompanying drawings, the invention resides in the novel elements,features of construction and cooperation of parts, as hereinafter moreparticularly pointed out in the claims.

In the drawings:

{FIGURE 1 is an elevational view of a stitch cam for a circular knittingmachine in accordance with the instant invention;

FIGS. 2, 3 and 4 are views illustrating the relation between the needlesand sinkers during certain phases of their operation to form loops of aknitted fabric; and

FIG. 5 is an elevational view of the needles and sinkers as seen fromthe right of FIG. 2 illustrating the operating relations of the needlesindicated in FIG. 1 with the sinkers cooperating therewith.

The needle operating cam structure of the instant invention ispreferably associated with a machine having both rotary andreciprocatory motion of the type in which independently operated latchneedles are moved to draw stitches over the upper surfaces of thesinkers such as that disclosed in my co-pending application Serial No.329,801, filed January 6, 1953, and in the corresponding British PatentNo. 790,141, published February 5, 1958 and hereinafter referred tocollectively as the Coile disclosure.

Referring to FIG. -1 of the drawing, there is shown a cam assembly 10for operating needles 11 to draw yarn in forming loops of a fabric andincluding an upper cam 12 and a lower or guard cam 15. ,The upper cam 12is provided with inclined draw-down surfaces 16 which are adapted toengage butt portions 14 of the needles 11 to draw them downwardly duringboth rotary and reciprocatory movements of the machine. The surfaces 16incline inwardly and downwardly toward each other to merge with outerends of short lower horizontal surfaces 17 which act on the butts 14 toposition the needles 11 at their maximum stitch drawing level.Intermediate the surfaces 17, the cam 12 is provided with inclinedsurfaces 22 extending outwardly and upwardly from an apex 25 to mergewith inclined surfaces 26 extending inwardly and upwardly from innerends of the surfaces 17 of the cam. The apex 25 is suitably spaced belowthe level of the surfaces 17 to draw the needles downwardly to a lowerposition during the formation of the loops as hereinafter set forth.

(The guard cam is provided with an upper horizontal surface 27 whichlies parallel to the surfaces 17 of the cam 12 and which is spacedtherefrom to provide clearance for the passage of the butts 14 of theneedles. Inclined surfaces 28 which extend inwardly and downwardly fromthe surface 27 to meet at a point opposite to the apex 25, act tocontrol the position of the needles 11 as they pass beneath the cam 12.The cam 12 and guard cam 15 are secured to a support member, indicatedin dot-and-dash outline at 30, by screws 31, the support member beingmounted for movements in the same manner as the cams in said Coiledisclosure to change the position of the cams in drawing stitches ofdifferent lengths.

During both rotary and reciprocatory movements of the machine, theneedles 11, after being raised to the latch clearing level, are loweredto receive yarn and then engage an inclined surface 16 of the cam 12 tobe drawn downwardly to the level of a surface 17 (FIGS. 1 and 5) to drawor measure the yarn for the new stitches over upper surfaces or nibs 32of a pair of sinkers 35 (FIG. 2) associated with each needle. As theneedles continue to move, the butts thereof ride ofi of the surface 17thereby relieving the tension in the stitches. At this time the leadingsinker of the pair of sinkers is moved to withdraw its nib 32 from thestitch. As the needles continue to move, the needle butts engage thesurface 22 and the needles are lowered to the level of the apex 25 topull or draw the newly drawn stitches over knockover surfaces 37 of thesinkers (FIG. 3) which hold the previously formed stitches as the newstitches are knitted therethrough. Immediately following movement of theneedles 11 to the level of the apex 25, they are raised by the inclinedsurface 28 of the guard cam 15 to the level of surface 27 of the guardcam 15 to thereby relieve the tension on the new stitches as the sinkers35 are advanced to catch and hold the new stitches in throat portions 40of the sinkers when the needles are again raised to latch clearing levelas indicated in FIG. 4.

It will be obvious that with the cam structure of the instant invention,the tension exerted on the stitches by the needles both at the initialstitch drawing level and at the knockover level is relieved to permitthe sinkers to move freely through the stitches. Further, the additionaldownward movement of the needles to draw the stitches over the knockoversurfaces of the sinkers acts to equalize the yarn in the stitchesthereby insuring the formation of stitches of uniform length.

It will be understood that the improvements specifically shown anddescribed by which the above results are obtained can be changed andmodified in various ways without departing from the invention disclosedand hereinafter claimed.

I claim:

1. In a circular knitting machine having independent latch needlesadapted to be operated in both rotary and reciprocatory movements of themachine and sinkers cooperating with said needles, said sinkers havingupper stitch drawing surfaces and lower knockover surfaces, incombination with a stitch cam having upper straight needle draw-downsurfaces for moving said needles to draw yarn stitches over the uppersurfaces of said sinkers during reciprocatory movements of said needlesin opposite directions, straight lower horizontal surfaces into whicheach of said draw-down surfaces merges, and corresponding to the maximumdepth to which said needles are moved to draw said stitches, a portionintermediate said horizontal surfaces having :draw-down surfaces formoving said needles to draw 'said stitches onto the knockover surfacesof said sinkers during reciprocatory movement of said needles inopposite directions, and upwardly inclined surfaces joining the innerends of said horizontal surfaces to said draw-down surfaces of saidintermediate portion, said upwardly inclined surfaces acting on saidneedles to relieve the tension in the stitches between the draw-downmovements of said needles by said upper draw-down surfaces and saiddrawadown surfaces of said intermediate portion.

2. In a circular knitting machine having independent latch needles andsinkers cooperating with said needles, said sinkers having an upperstitch drawing surface and a lower knockover surface, in combinationwith a stitch cam having an upper downwardly extending needle drawdownsurface for drawing yarn stitches over the upper surfaces of saidsinkers, a straight horizontal surface merging with the lower end ofsaid draw-down surface, a second needle draw-down surface extendingupwardly from a point below the level of said horizontal surface fordrawing said yarn stitches onto said knockover surfaces of said sinkers,and an upwardly inclined surface joining the inner end of saidhorizontal surface and the upper end of said second draw-down surface,said upwandly inclined surface acting on said needles to relieve thetension in the stitches between the draw-down movements of said needlesby said upper and second draw-down surfaces of said cam.

References Cited in the file of this patent UNITED STATES PATENTS Re.20,423 Robaczunski June 22, 1937 521,367 Gilbert June 12, 1894 1,183,604Swinglehurst May 16, 1916 1,209,256 Bosworth Dec. 19, 1916 1,209,257Bosworth Dec. 19, 1916 1,813,849 Guillemot July 7, 1931 2,043,852 HolmesJune 9, 1936 2,762,213 Schurich Sept. 11, 1956

1. IN A CIRCULAR KNITTING MACHINE HAVING INDEPENDENT LATCH NEEDLESADAPTED TO BE OPERATED IN BOTH ROTARY AND RECIPROCATORY MOVEMENTS OF THEMACHINE AND SINKERS COOPERATING WITH SAID NEEDLES, SAID SINKERS HAVINGUPPER STITCH DRAWING SURFACES AND LOWER KNOCKOVER SURFACES, INCOMBINATION WITH A STITCH CAM HAVING UPPER STRAIGHT NEEDLE DRAW-DOWNSURFACES FOR MOVING SAID NEEDLES TO DRAW YARN STITCHES OVER THE UPPERSURFACES OF SAID SINKERS DURING RECIPROCATORY MOVEMENTS OF SAID NEEDLESIN OPPOSITE DIRECTIONS, STRAIGHT LOWER HORIZONTAL SURFACES INTO WHICHEACH OF SAID DRAW-DOWN SURFACES MERGES, AND CORRESPONDING TO THE MAXIMUMDEPTH TO WHICH SAID NEEDLES ARE MOVED TO DRAW SAID STITCHES, A PORTIONINTERMEDIATE SAID HORIZONTAL SURFACES HAVING DRAW-DOWN SURFACES FORMOVING SAID NEEDLES TO DRAW SAID STITCHES ONTO THE KNOCKOVER SURFACES OFSAID SINKERS DURING RECIPROCATORY MOVEMENT OF SAID NEEDLES IN OPPOSITEDIRECTIONS, AND UPWARDLY INCLINED SURFACES JOINING THE INNER ENDS OFSAID HORIZONTAL SURFACES TO SAID DRAW-DOWN SURFACES OF SAID INTERMEDIATEPORTION, SAID INWARDLY INCLINED SURFACES ACTING ON SAID NEEDLES TORELIEVE THE TENSION IN THE STITCHES BETWEEN THE DRAWN-DOWN MOVEMENTS OFSAID NEEDLES BY SAID UPPER DRAW-DOWN SURFACES OF SAID DRAW-DOWN SURFACESOF SAID INTERMEDIATE PORTION.